Wild spring ride in Ontario to bring thunderstorms, rain and snow
The next few days are forecast to bring dynamic and changing weather across southern Ontario, showcasing the volatility of spring
Southern Ontario will get a good taste of spring this week, both the ups and downs that it can bring each year.
That means warmth, heavy rainfall and a thunderstorm risk early this week, along with a cooldown and even some snow for some areas in Ontario.
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Going forward into April, it appears that spring will continue to test our patience as we get deeper into the month. The roller-coaster is going in the right direction, though, as the dips won’t be as cold and the peaks are getting warmer. But the consistent, warmer-than-normal weather is not expected.
Thunderstorms, heavy rain and snow this week
By Monday, a light, southerly flow bumps up temperatures, pushing temperatures well above seasonal (10+ degrees in some cases).
Temperatures are likely to push into the low 20s across extreme southwestern Ontario (Sarnia, Windsor), while temperatures in the upper teens are likely near the Niagara Escarpment, aided by gusty, westerly winds.
On Monday night, the thunderstorm risk increases across southwestern Ontario, thanks to an upper wave migrating into the area, providing increasing moisture and a more unstable air mass.
Gusty winds and small hail are the primary threats with the initial pulse of convection.
On Tuesday, the surface low is forecast to cross southern Ontario, and it will be a catalyst to develop more convection chances along and ahead of the surface cold front.
Two biggest chances for thunderstorms will be early and late Tuesday, extending into the evening.
This low will advance warm air north, giving locations away from Lake Ontario the opportunity to reach the warmest temperatures of the year (approximately 20°C for Toronto).
Locally heavy rain could cause ponding and issues across roadways, impacting the Tuesday evening commute corridors across southern Ontario.
Up to 30-50 mm of rainfall is possible in regions that see multiple rounds of thunderstorms.
Niagara Peninsula to London also has a higher rainfall signal (locally 50+ mm). Unlikely to be a washout, though, with ample breaks in precipitation forecast through the day, but when it rains, it’s likely to pour.
The threat of snowfall with this system is well north, impacting the Timmins and Kapuskasing area.
After the cold front passage on Wednesday, temperatures fall back to seasonal along the 401 and well below seasonal across northeastern Ontario.
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We will closely watch a system that is expected to track south of the region late Thursday through early Friday, with a risk for showers and possibly mixed precipitation (snow and ice), depending on the storm track.
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A strong low-pressure system is expected to track into the Great Lakes region during the Easter weekend. That should bring a brief surge in temperatures, along with windy conditions and periods of rain and thunderstorms. Another strong cold front is expected as the storm departs with colder weather returning on Easter Monday, and beyond.
Changeable temperatures will continue through April, which is normal, but at this point, it appears that temperatures will tip to the cool side of seasonal during mid- and late April.